Cam plastometer



July 29, 1969 E. E. HAHN ET AL 3,457,779

A CAM PLASTOMETER Filed July 13, i967 s sheets-sheet 1 July 29, 1969 E,E, HAHN ET AL 3,457,779

CAM PLASTOMETER Filed July 15. 1967 Y s sheets-sheet 2 INVENTORS. EDWARDE.HaHN,

ERIC/c H. Kanu-R and BY K/vosHl Non/KANA- July 29, 1969 E; E. HAHN ETA1- 3,457,779

CAM PLASTOMETER Filed Julg,1 l5, 1967 5 Sheets-Sheet 5 Fig. 6.

INVENTORS EDwnRn E HAHN, EmcK H. KosLLs'R d BY KlyosHl Non/KANE UnitedStates Patent O 3,457,779 CAM PLASTOMETER Edward E. Hahn, Glenview,Erick H. Koeller, Chicago,

and Kiyoshi Norikane, Park Forest, Ill., assignors, by

mesne assignments, to the United States of America as represented by theSecretary of the Navy Filed `luly 13, 1967, Ser. No. 653,281 Int. Cl.G01n 3/10 U.S. Cl. 73-94 9 Claims ABSTRACT OF THE DISCLOSURE A machinefor producing compression deformations of flat and cylindrical materialspecimens having a rotating cam to provide the deformation control of apress, the energy of the press being supplied 4by a power ram restrainedby the rotating cam with latching means for holding the press out ofoperation of the cam and ram and to allow a single press or multiplepresses to be effected at the speed of the cam under the speedstabilization of a flywheel.

BACKGROUND OF THE INVENTION This invention relates to a material pressor plastometer which is a machine or mechanism to produce plasticcompressive deformations of materials. This basically simple taskbecomes complicated when high load requirements become coupled with highstrain rates of predetermined and controlled nonconstanttime/displacement characteristics.

Existing compressive loading units can be categorized into three -basicgroups as follows: (l) Slow operating constant deflection rate unitsthat can be mechanically driven by conventional motors and reducers. Theexpenditure of energy being spread out over a long period of time keepsthe power requirement in a reasonable range and can thus be supplieddirectly. (2) Impact hammers which are driven by gravity, mechanicalsprings, or pneumatic springs to supply deformation forces. However, thedegree and rate of deformation is a random characteristic depending onhammer weight, impact velocity, specimen configuration, and themechanical properties of the special material. (3) Controlleddeformation of a compression specimen obtained by the action of a camprofile moving at a constant angular speed. In order to use this conceptfor test involving high strain rates, the required energy is obtainedfrom high speed flywheels which also serve to minimize speedfluctuations. These units become very bulky requiring heavytransmissions, etc., when strain rate versatility is required.

SUMMARY OF THE INVENTION The concept for a plastometer of this inventioncornbines some of the advantages of some of the above discussed groupsfor obtaining compressive deformation at a controlled variable rate. Arotating cam is utilized to provide the deformation control, but it doesnot supply energy or power needed to deform the specimen. A powersupplying ram is restrained by the cam so that the ram has a tendency toaccelerate the cam during the compressive stroke. For this reason thespeed controlling the enertia effect of a simplified flywheel system isused to control cam rotation velocity. VThe actual test deformation ramforce is provided by a high pressure air piston with a short workingstroke and a proportionally high ahead volume. By precharging this headvolume to any desired gas or air pressure, a pneumatic spring isproduced that is capable of exerting the required forces while itstravel speed (including acceleration, etc.) is controlled by a camfollower incorporated in the piston rod extension.

ice

By means of remotely controlled sears and latches, the piston iscontrolled to provide a single or multiple stroke operation. It isaccordingly a general object of this invention to provide a plastometerhaving a pneumatically controlled compressive force controlled in speedof compression by a cam profile and with sears and latches arranged topermit single or multiple stroke operation.

BRIEF DESCRIPTION -OF THE DRAWINGS These and other objects and theattendant advantages, features, and uses will become more apparent tothose skilled in the art as a more detailed description proceeds whenconsidered along with the accompanying drawings, in which:

FIGURE 1 is a side elevational View with parts broken away and partsshown in section to illustrate the device of this invention;

FIGURE 2 is an end elevational view with parts broken away and partsshown in section looking into the right hand end of FIGURE l;

FIGURE 3 is a greatly enlarged sectional view of the sear means andrelated parts shown `in FIGURE l;

FIGURE 4 is a greatly enlarged bottom view of the Sear means and relatedparts looking upwardly, as shown by the arrows of the sectional line 4-4in FIGURE 3;

FIGURE 5 is an enlarged cross-sectional view of the latching means andrelated parts shown in FIGURE 1 on a sectional line 5 5 of FIGURE 3looking in the direction of the arrows; and

FIGURE 6 is a partially elevational and partially sectional enlargedview of the compression and xed jaws of the plastometer as shown inFIGURES 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly toFIGURES 1 and 2, the plastometer device is supported in a frameworkconsisting of a base plate 10 supporting an upper mounting plate 11 by aplurality of posts or rods 12. On the base plate 10 is mounted a motorpower means such as an electric motor 13 coupled through a gearreduction means 14 to rotate a shaft 15 on which is fixed a pulley 16.The pulley 16 has a belt 17 driven by the pulley 16 to drive a pulley 18on a shaft 19 that is journaled in two bearing journals and 21 supportedon the underside of the mounting plate 11 by bolting, or other suitablemeans. The pulley 16 is of a larger size than the pulley 18 to producean increase of speed of 'the shaft 19 over the shaft speed 15. Thesepulleys are interchangeable to allow the reverse effect to be producedfor precisely controlled low strain rates tests. The shaft 19 has a camwheel 22 mounted thereon between the journals 20 and 21 and is supportedin position on the shaft 19 by a mounting flange 23 which is bolted orotherwise suitably fastened to the cam wheel 22 so that cam wheel 22 maybe replaced by other cam Wheels having different cam surfaces 24. Camsurface 24 consists of a short diameter surface 24', a long diametersurface 24", and controlled transitions between these surfaces. Camwheel 22 also has cam blocks 2S and 26 mounted on the side peripherythereof in a position and for the purpose soon to be described. Shaft 19also has a pulley 27 thereon with a belt, or preferably a plurality ofV-belts, 28 surrounding the pulley 27 and a pulley 29 on a shaft 30supported by a pair of journals 31 and 32 on top of the mounting plate11 to drive a heavy ywheel 33. The pulley 27 is much larger than thepulley 29 to provide an increase in speed of shaft 30 over the speed ofshaft 19 to give flywheel 33 a high angular velocity.

0 When the motor 13 is energized, pulley 16 driving through 3 speed ofthe heavy flywheel 33 to produce a substantially constant angularvelocity of cam wheel 22.

Mounted on top of the mounting plate 11 is a housing or cage of squareor rectangular conliguration exactly overlying a corresponding opening34 in the mounting plate 11. Within this housing 35 is a cam followersupport 36 on which is journaled a cam follower roller 37 by a bearingor journal pin 38. The cam follower support 36 is substantially hollowor U-shaped with a crosshead 38 near the upper end thereof on which issupported a compression jaw 39 fixed in a manner, as will be later moreparticularly described with reference to FIGURE 6. The cam followersupport has circular openings or windows 40 through opposite walls inthe area of the compression jaw 39 so that he compression jaw 39 may beviewed from the outside of the mechanism. Below the compression jaw 39and crosshead 38 is a hollow portion 41 through which is supported abase plate 42 on which is -mounted a lixed jaw 43. The base plate 42 ismounted on brackets xed to the mounting plate 11 by bolting, or anyother suitable manner, the bracket 44 also having a work table 45mounted thereon which is in the same plane as the top of the xed jaw 43so that material to be pressed may be slid on the work table 45 to bringthe material between the jaws 39 and 43 for the pressing operation. Thecam follower support is normally held in a position in which the camfollower roller 37 just clears the cam wheel surface 24 by sear means 46and 47, later to be described more fully in the detailed description ofFIGURE 3.

Mounted on top of the cage or casing 35 is a fluid or pneumatic powercylinder 50 which may be mounted by flange means 57 with bolts or othersuitable means for positioning the cylinder 50 directly over the cage orcase 35. The pneumatic cylinder has a piston 52 reciprocably mountedtherein with a power shaft 53 extending through an opening in the lowerwall of the power cylinder 50 and journaled by a pin 54 to the upper endof the cam follower support 36. The power cylinder 50 is ofsubstantially short stroke but of considerably large piston area toprovide high energy compression in the manner of a pneumatic spring onthe cam follower support 36. The piston chamber between the uppercylinder wall and the top of the piston 52 has a port 55 coupled througha fluid conduit, through a supply and exhaust valve 56, and a pressureregulator 57 to a fluid pressure source, such as air under pressure. Thelluid pressure on the cylinder may be preset by pressure gage 58 andadjustment of the regulator 57, whenever the supply and exhaust valve 56is rotated to admit air under pressure to the piston chamber, as shownin solid lines in the valve 56. Whenever it is desirable to relieve thepressure from above the piston 52, the supply and exhaust valve 56 maybe rotated, as shown by the broken lines therein to connect the pistonchamber with the exhaust port. When the sears 46 and 47 become operativeto release the cam follower 36, 37, the cam follower will proceedthrough one cycle or one revolution of the cam wheel 22 and then belatched in its uppermost position by latch means 59 and 60, shown inFIGURE 2, the construction and operation of which will be more fullydescribed in connection with FIGURE 5. When material is to be placedbetween the jaws 39 and 43, this material is laid on table 45 with theportion to be pressed between the jaws 39 and 43 and the air pressureregulated by the regulator 57 and supplied to the piston chamber abovepiston 52 through the supply valve 56. The piston is then held as apneumatic spring by the sear means 46 and 47 on the cam follower 36, 37until the sear means are released to permit the cam follower roller 37to ride directly on the cam wheel 22 surface 24 and control the downwardstroke of the compression jaw 39 on the work piece in accordance withthe pressure exerted by the piston 52. As the cam follower 36, 37follows the cam surface 24 in the downward stroke, the latch means 59and 60 will be released such that when the cam follower roller 36returns to the high portion of the cam surface 24, the latch means 59and 60 will catch the cam follower support and hold it against furthercam follower travel, as will later become clear in the description ofthe FIGURES 3, 4, and 5. As may be seen in the description of FIGURES land 2, the cam follower 36, 37 is released to follow the cam surface 24and as the follower roller 37 proceeds towards a shorter diameter of thecam wheel 22 it will tend to accelerate the rotation of the cam wheel22, but this tendency to accelerate is opposed by the action of theheavy flywheel 33 thereby keeping the cam wheel 22 at a substantiallyconstant angular velocity.

Referring more particularly t0 FIGURES 3 and 4 there is shown a greatlyenlarged view of the sear means 46 and 47 of FIGURE l. The sear meansconsists of a pair of lever arms 60 and 61 pivoted at their upper endsby journals 62 and 63 in block members 64 and 65 mounted by cap screwsor other suitable means to the lower side of mounting plate 11. Eachlever 60 and 61 has a shoulder portion 66 and 67 which underlies thelower ends of the cam follower support 36. On the lower end of eachlever 60 and `61 is mounted a rocker arm 68 and 69, respectively, as bystud bolt journals or any other suitable means. In a slotted opening onthe inner end of each rocker arm is mounted a cam follower roller on therocker arm 68 and a similar roller 71 on the rocker arm 69. On the outerend of each rocker Varm 68 and 69 is a connecting link 72 and 73,respectively, the lower end of each of which is coupled by a cross bar74 having an armature 75 allxed thereto which is operative in anelectromagnet device 76. The cross bar 74 is biased away from theelectromagnet by a spring 77 to hold the rocker arms 68 and 69 in aposition shown by the broken line arcs to hold the cam follower rollers70 and 71 out of engagement with the cam blocks 25 and 26, as shown inFIGURES l and 3. Whenever the electromagnet 76 is energized, the crossbar 74 is pulled downwardly pulling the links 72 and 73 along to rotatethe rocker arm 68 clockwise and the rocker arm 69 counterclockwiseclosing the gap between the cam follower rollers 70 and 71 to bring themin a position to ride up the cams 26 and 25, respectively. When camrollers 70 and 71 ride up cam blocks 26 and 25, respectively, the leverarms 60 and 61 will be rotated outwardly to disengage the sear portions66 and 67 from under the cam follower support 36 allowing the camfollower roller 37 to engage the cam wheel surface 24. As may be seen inFIGURE 2, this operation of releasing the sears from the cam followersupport 36 is at a point on the cam wheel cylindrical surface 24 justpreceding its reduction in diameter portion 24 so that there will be nohammer effect between the cam follower and cam wheel surface since thecam follower is retained by the sears at a very close tolerance such as.005 of an inch above the cam surface at its cylindrical diameter.Energization of the electromagnet 76 will cause release of the searmeans 46 and 47 but more than one cycle of compression on the work pieceby the compression jaw 39 may be obtained by continuing the energizationof the electromagnet 76, as will later be described.

Referring more particularly to FIGURES 4 and 5, the latch means 59 and60` is comprised of heavy lever means 81 and 82, journaled by pins 83and 84 on their lower ends in brackets 85 and 86 supported by cap screwsor other means to the underside of the mounting plate 11. The upper endof each lever arm 81 and 82 has a shoulder portion 87 and 88,respectively. The pins 83 and 84 have mechanical means thereon, as shownby broken lines 89 and 90, between the armature of electromagnets 91 and92 biased by springs 93 and 94 to rotate the lever arms 81 and 82 intothe path of the cam follower support 36. The cam follower support hasnotches 95 and 96 milled into the bottom of the cam follower support 36,as shown, to effect this latching means. The

latch 81 is retained out of latching position by a dog 97 and the latch82 is retained out of latching position by the dog 98, these dogs beingbiased in a latching position by springs 99 and 100, respectively. Eachdog has a projecting portion 101 and 102 in the path of the cam followersupport 36 such that whenever the sear means 46 and 47 release the camfollower 36, 37 to follow the cam surface 24 the projections 101 and 102of the dogs 97 and 98 are rotated downwardly against the springs 99 and100, respectively, to release the latches 81 and 82 to ride against theouter surface of the cam follower support 36 by the bias of springs 93and 94, respectively. When the diameter of the cam wheel 22 increases toits highest point 24", latch'81 will fall under the notch 95 and latch82 will fall under the notch 96 to hold the cam follower support 36 inits upper position. The long diameter portion 24 of cam surface 24 isshown exaggerated in FIGURE 2` but may be in the order of ,010 longerthan the normal cylindrical surface. While the electromagnets 91 and 92are shown separately for convenience herein, a single electromagnet maybe used by the couplings89 and 90 connecting both pins 83 and 84 to thesingle electromagnet. The above described cam follower 36, 37, whenreleased by the sear means 46, 47, will go through one cycle or onerevolution around the cam surface 24 of cam wheel 22 and then be latchedout of further operation. When latch means 59, 60 are holding the camfollower in its uppermost position, the sear means 46, 47 can engage andhold cam follower 36, 37. The latches may be reset by energization ofelectromagnets `91 and 92 to rotate the latch lever 81` counterclockwiseand the latch lever 82 clockwise until the dogs 97 and 98 again latchthese levers' out of the path of the cam follower support 36.

Referring more particularly to FIGURE 6, the crosshead portion 38 in thecam follower support 36 supports the compression jaw 39 in any suitablemanner, herein shown to be stud bolts 105. Between the web portion 38and the compression jaw 39 may be placed a block 106 with a plurality ofparallel cylindrical openings 107 into which may be placed electricalheating elements 108. Heating elements 108 may be energized to cause thecompression jaw 39 to be heated to a desirable temperature. In likemanner the fixed jaw 43 may be supported on its support 42 by cap screws109, or any other suitable means, as desired. In like manner a block110, having a plurality of parallel cylindrical openings similar to orthe same as the block 106, has heating elements 108 for the purpose ofheating the xed jaw 43. Heating of these jaws may be desirable wherethermoplastic material is to be compressed between the jaws 39 and 43.

OPERATION While the operation of the press may be obvious from the abovedetailed description of the several figures, let it be assumed byreference to FIGURES 1 and 2 that motor 13 is energized to bring the camwheel 22 up to a constant speed which is maintained stable by the heavyllywheel 33. Supply and exhaust valve 56 is placed to pressurize thepiston chamber above piston 52 at a pressure set by regulator 57 for theparticular material to be compressed by the jaws 39 and 43. When a pieceof the material to be pressed is laid on work table 45 and between thejaws 39 and 43, the electromagnet 76, as shown in FIGURE 4, may beenergized to swing the rocker arms 68 and 69 into position shown by thebroken line arcs to cause the cam blocks 25 and 26 to remove the sears66 and 67 from under the cam follower support 36 releasing the camfollower to allow roller 36 to engage cam wheel surface 24 as cam wheel22 rotates in the direction of the arrow shown in FIGURE 2. The powercylinder 52 will force the compression jaw 39 downwardly as rapidly asthe cam surface 24' will permit cam follower wheel 37 to follow untilcomplete compression is exerted on the work piece. The greatest pressurewill be exerted on the work piece whenthe cam follower wheel 37 is atthe shortest diameter of the cam surface 24 and thereafter the camfollower will be forced upwardly until it reaches the greatest diameterof cam surface 24". In the downward travel of the cam follower support36 the dogs 97 `and 98 are forced out of holding position for thelatches 81 and 82 so that when the high diameter cam surface 24" isreached the cam follower 36, 37 is returned to its high position atwhich time latches 81 and 82 fall into the notches 95 and 96 to retainthe cam follower in its upper position. If electromagnet 76 is heldenergized and electromagnets 91 and 92 are energized in quick successionthe sear means 46, 47 will be held in position to have the cam followerroller 70 and 71 to engage the cam blocks 25 and 26 repeating therelease of the cam follower support 36 for rapid repeated compressionsby the jaws 39 and 43. If electromagnet 76 is momentarily energized orheld energized the cam follower 36, 37 will travel through just onecycle and be locked up by the latch means. Accordingly, the operator cancontrol the cam plastometer to make a single stroke compression as hefeeds the material under the jaws 39 and 43 or he can operate the deviceto produce repeated compressions on the same portion of the work pieceor as the work piece is fed through the jaws 39 .and 43. By this meansoverloading of the machine is prevented when pressing unknown materialswhere resulting loads may exceed the load capabilities designed into themachine. If the specimens reaction to loading exceeds the force suppliedby the air cylinder ram, the ram will stall out and thus lift the camfollower 36, 37 from the cam surface 24' which normally controls thedeformation profile and thus avoid overload damage.

While many modifications and changes may be made in the constructionaldetails and features of this invention in carrying out the spirit ofthis invention, it is to be understood that we desire to be limited inthe scope of our invention only by the limits of the appended claims.

We claim:

1. A cam plastometer comprising:

a journaled cam wheel driven in angular rotation by motive means;

a flywheel coupled to said journaled cam wheel and driven thereby tostabilize the angular rotation 0f said cam wheel;

a cam follower engagable with said cam wheel, said cam follower havingan extension supporting a compression jaw oriented to advance incompressive force toward said cam wheel;

a power cylinder coupled to said extension to power said cam followertoward said cam wheel;

a tixed jaw under said compression jaw to be engaged by said compressionjaw when said cam follower is powered by said cylinder toward said camwheel;

sear means engagable with said cam follower to hold said cam followerfrom following said cam wheel, said sear means having a remotelycontrolled actuator to actuate said sear means to be released by saidcam wheel to allow said cam follower to follow said cam wheel; and

latch means engagable with said cam follower to hold same free of saidcam wheel, said latch means having dogs biased to hold said latch meansout of engagement with said cam follower, said dogs having a portion inthe path of said cam follower to release said dogs from holding saidlatch means out of engagement of said cam follower whereby said camfollower will be enabled to follow said cam wheel through one cycle ofrotation before being latched by said latch means.

2. A cam plastometer as set forth in claim 1 wherein:

said flywheel is coupled to said journaled cam wheel by pulleys andbelts, said pulleys being associated in size to cause said ywheel torotate a higher angular velocity than said cam Wheel.

3. A cam plastometer as set forth in claim 2 wherein:

said cam follower constitutes a roller element in a follower supportwith said roller element engagable with said cam wheel, and said camwheel has a cam surface that is circular over a portion thereof and aportion of gradual reduction in diameter to a low diameter point.

4. A cam plastometer as set forth in claim 3 wherein:

said power cylinder is a fluid cylinder with means to regulate the fluidpressure and thereby control the exerted power of said uid cylinder.

5. A cam plastometer as set forth in claim 4 wherein:

said compression and fixed jaws each have heating elements embeddedthereunder whereby the jaws may be heated to a predeterminedtemperature.

6. A cam plastometer as set forth in claim 5 wherein:

said sear means are a pair of pivotal levers, each having a shoulderportion adaptable to underlie said cam follower support opposite thepivot thereof, each lever having a rocker arm centrally pivoted normalto the pivot of said pivotal levers and having a cam Afollower portionin the path of the peripheral sides of said cam wheel, the peripheralsides of Said cam wheel each having a cam surface thereon, said rockerarms being mechanically coupled to be rocked to place each cam followerportion in the path and out of the path of said cam surfaces wherebyrotation of said rocker arms for engagement of said cam fol lowerportion with said cam surfaces on said cam wheel releases said shouldersunderlying said cam follower support to allow said cam follower tofollow said cam wheel.

7. A cam plastometer as set forth in claim 6 wherein:

said latch means includes a pair of lever arms diametrically opposedabout said cam follower with the pivot of each on the lower end and theupper end engagable with the bottom edge of said cam follower support,each lever having a dog spring biased to hold each lever out of the pathof said cam follower support and having a portion on said dog engageableby the cam follower support in its downward travel to release saidlevers to latch and hold said cam follower support when said cam wheelreturns said cam follower to its uppermost position of travel wherebysaid cam followers, upon being released by said sear means, will followthe surface of said cam wheel pushing said dogs to release said latchmeans levers t0 .ride against said cam follower support until said camwheel surface forces spaid cam follower to its uppermost position atwhich time said latch means levers engage said bottom edge of said camxfollower support restraining it from downward movement.

8. A cam plastometer as set forth in claim 7 wherein:

said sear means and said latch means are actuated by electromagneticmeans.

9. A cam plastometer as set forth in claim 8 wherein:

said cam follower portion on said `rocker arms are rollers.

References Cited UNITED STATES PATENTS 1,288,746 12/1918 Thacher 73-942,669,119 2/1954 Dodge 73-100 RICHARD C. QUEISSER, Primary Examiner C.E. PHILLIPS, Assistant Examiner

